     (not (#+clj identical? #+cljs keyword-identical? op :is))
     (update-in [2] collect)))
 
-(defn applicable-delta
-  "Bring a delta from diagnostic form into applicable form."
+(defn summable-delta
+  "Make a diagnostic applicable for add again."
   [[op korks new-val :as delta]]
   (if (seq korks)
     delta

(defn diagnostic-delta
  "Bring delta into diagnostic form [op ks (v | [v+])].  v is a
  collection for :in and :ex ops.  This form is not applicable for add
  as ks can be [], which is invalid.

  Not suitable for :batch deltas (use unpack) beforehand."
  [[op korks-or-new-val new-val :as delta]]

  [ks]
  (if (coll? ks) ks [ks]))

;; Adding deltas
(defn- add-root-delta
  [val op new-val]
  (case op
